JPS60193313A - Direct current electric apparatus filled with oil - Google Patents

Abstract

PURPOSE:To make electric field distribution adjacent to a connecting point uniform by enveloping the outside of an insulation shield provided at the outside of an insulated high voltage lead wire and the bottom of a bushing with an insulation barrier the one end of which is connected to the high voltage lead wire. CONSTITUTION:In the tank 11 of a direct current transformer filled with oil, a coil 11b wound around an iron core 11a is housed and a bushing 13 is installed on a bushing pocket 12 attached to the tank 11. Insulation oil 11c is filled in the tank 11 and the pocket 12. At the bottom of the bushing 13, i.e., the lower terminal 14 in the oil, an insulation shield 15 is provided and the terminal 14 and the coil 11b are connected with an insulated high voltage lead wire 16 consisting of a lead wire 16a with an insulation layer 16b. The vicinity of the connecting point 17 of the lead wire 16 and the terminal 14 and the outside of the shield 15 are enveloped with an insulation barrier 18, the one end of which is fixed on the lead wire 16. This reduces the electric field of the lower end of the bushing 13 and the electric field of the lead wire 16 and improves withstand voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to DC oil-filled electrical equipment, and particularly to an improvement in the insulation structure near the connection portion with an insulated high voltage lead wire at the bottom of a bushing.

[Technical background of the invention and its problems]

BACKGROUND ART Recently, the development of blood flow power transmission has been progressing due to its advantages such as low cost of line construction and advantageous for transmitting large amounts of power over long distances. Among these DC power transmission equipment, many DC oil-filled electric devices, such as transformers for DC power transmission, have an oil-filled and insulated structure.

Such an oil-filled insulated structure is designed based on a transformer for AC power transmission, while solving insulation problems specific to transformers for DC power transmission.

However, in recent years, there has been an increase in DC transmission voltage and power transmission capacity, and in order to cope with these problems, high-voltage, large-capacity transformers are being considered with various innovations. There is. In this case, a major problem is that of DC withstand voltage as the voltage increases.

As is well known, the voltage distribution of DC voltage is determined by the resistivity of the material. This is compared to cases where the voltage distribution is determined by the dielectric constant of the material, such as with AC voltage.
A big difference occurs in the voltage distribution. In terms of material strength, insulating oil is extremely weak compared to oil-impregnated paper in the case of DC voltage.

On the other hand, in the case of AC voltage, insulating oil and oil-impregnated paper have almost the same characteristics, or oil-impregnated paper has slightly stronger characteristics. Direct current i of insulating oil
The voltage of the four companies is lower than the AC side voltage, and the DC withstand voltage of oil-impregnated paper is several times the countercurrent withstand voltage. For this reason, DC insulation structures that take advantage of the characteristics of insulating materials and potential distribution have been devised and put into practical use.

However, the insulation structure of transformers for alternating current power transmission, which is completely unreliable, has some parts that are problematic in transformers for direct current power transmission. In a transformer, this is the connection area between the insulated high-voltage lead wire connected to the coil of the transformer body and the oil-filled bushing, or the area around the insulating shield of the oil-filled bushing. In these parts, as shown in Fig. 1, the oil-immersed side of the oil-filled bushing 1, that is, the lower terminal 2, is connected to the insulated high-voltage lead wire 3, which is connected to the transformer main body coil (center not shown). An insulating shield 5 is connected to the lower terminal 2 in order to alleviate the electric field around the connection part 4. The oil-filled bushing 1 houses a center conductor 7 that supports an insulating core 7a inside a lower insulator tube 6, and is filled with insulating oil 8. The electric field distribution 9 in the vicinity of the connection portion 4 has a significant concentration of DC electric field as shown by the dotted line, and there is a problem in the insulation structure that needs to be solved.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and its object is to provide a DC oil-filled electric appliance with excellent DC withstand voltage and a simple insulation structure.

[Essentials of invention]

In order to achieve this purpose, the present invention surrounds the outer periphery of an insulating shield provided at the connection between the lower part of the bushing and the insulated high-voltage lead wire and the lower end of the bushing, and connects one end to the insulated high-voltage lead wire. It is characterized by a simple insulating structure with a uniform electric field distribution near the connection part and improved self-current withstand voltage by providing a fixedly attached insulating barrier.

It is preferable to provide a relationship of 2L between the axial length of the insulation barrier and the axial length Ll of the insulation shield.

Angle at-4 between the horizontal axis and the inclined part of the insulation barrier between the outer periphery of the insulation shield and the outer periphery of the insulated high voltage lead wire
Preferably, the angle is between 50 and 60 degrees.

It is preferred that the insulated high voltage lead wire be insulated in a taper from the attachment point on the insulated high voltage lead wire at the portion rejected by the insulation barrier to the lower terminal of the bushing.

[Embodiments of the invention]

Hereinafter, nine examples of the DC oil-filled electrical equipment of the present invention will be explained with reference to FIGS. 2 to 5. Examples of DC oil-filled electrical equipment include transformers, reactors, and bushings, and among these, a DC oil-filled transformer will be explained. In FIG. 2, the transformer body, that is, the iron core 1 is inside the transformer tank 11.
A bushing 13 is attached to a bushing pocket 12 attached to a transformer tank 11, and an insulating oil 11C is filled inside the transformer tank 11 and bushing pocket 12. . An insulating shield 15 is attached to the lower end of the bushing 13, that is, the lower terminal 14 on the oil side, and the lower terminal 14 and the coil Ilb are connected by an insulated high voltage lead wire 16. The vicinity of the connection part 17 between the 1115 m high voltage lead wire 16 and the lower terminal 14 and the outer periphery of the insulation shield 15 are surrounded by the insulation barrier 1b as described later, and one end of the insulation barrier 18 is connected to the insulation high voltage lead powder 16. I'll start taking it. In addition, a 15M layer 16b is formed by wrapping an insulating paper around the lead wire 16a of the 16 insulated high-voltage lead wires.
It consists of

Further, in FIG. 3, a center conductor 21 having an insulating core 218 is housed inside the oil-submerged insulator tube 20 in the lower part of the bushing 13, that is, on the oil-submerged side, and this central conductor 21 is connected to the lower terminal 14. , insulating oil 2 inside the lower insulator tube 20
1b is filled. An insulating shield 15 is attached to the lower terminal 14 of the bushing 13, and an insulated high voltage lead wire 16 is connected to the coil llb of the transformer main body.
is attached to the lower terminal 14 via the attachment fitting 14a.

The insulating barrier 18 is formed into a funnel shape using a fibrous insulating material such as a press board, and one end of the insulating barrier 18 is fixed to the insulated high-voltage lead wire 16 via a mounting portion 22. A cylindrical portion 18b is formed through the formed inclined portion 18a. This cylindrical part 1
8b is formed to surround a portion of the lower side of the bushing 13, the connecting portion 17, and the outer periphery of the insulating shield 15.

Further, the insulating shield 15 forms an insulating member layer 15b in which the outer periphery of the ring-shaped conductor 15a is covered with an insulating member, and is attached to the lower terminal 14 of the bushing 13 via a mounting bracket 15c connected to the ring-shaped conductor 15Jl.

When the axial length of this insulating shield 15, that is, the length along the longitudinal direction of the center conductor 21 of the bushing 13 is Ll, and the axial length of the cylindrical portion 18b of the insulating barrier 18 is , L, medium 2L. Further, a tapered insulating portion 16C is formed in which the insulating layer 16b of the insulated high-voltage lead wire 16 on the lower terminal 14 side from the attachment portion 22 of the insulated high-voltage lead wire 16 of the insulating barrier 18 is tapered insulated with a slope. Furthermore, the mounting part 22
The inclination of the inclined part 18H between the insulating high voltage shield and the cylindrical part 18b forms an angle θ of 45° to 60° between the inclined part 18a and the horizontal axis indicated by the dashed line perpendicular to the insulating high voltage shield. .

Next, the effects of the present invention will be explained. In FIG. 4, the electric field E of the lower terminal 14 indicated by the dotted line in FIG.
, and the horizontal axis is the length Lttl'' of the cylindrical portion 18b of the insulation barrier 18. Here, the scale of the horizontal axis is the insulation shield 1.
The length of 5 is taken as an integer multiple. The relationship between the electric field b1 and the length of the cylindrical portion 18b is as shown in curve -■. That is, the electric field disease tends to be reduced as the length of the cylindrical portion 18b becomes longer.

In addition, the electric field E decreases markedly as the length increases from 0 to 2L1, and tends to be somewhat saturated in a longer range. The length L of the cylindrical part 18b of the insulating barrier 18 is
! was selected to be 2L out of L2.

In addition, regarding the insulation barrier 18, the insulation high voltage lead wire 16
The angle θ between the outer periphery of the insulating shield 15 and the outer periphery of the insulating shield 15, that is, the inclined portion 18a and the horizontal axis is 45°.
The reason for this selection is the following energization. That is, as shown in FIG. 5, the electric field H! of the insulated high voltage lead wire 16 is plotted on the vertical axis. (Refer to 3rd groan) Take 1. If the angle θ of the inclined portion 18a is plotted on the horizontal axis, the relationship between the two becomes like a curved line. As shown in this curved line, the electric field E2 changes depending on the angle θ, and particularly shows a tendency to decrease significantly when θ is between 0 and 456. Therefore, the angle 0 may be 45 degrees or more, but considering workability, it is considered appropriate that the angle 0 is between 45 degrees and 60 degrees, so the angle θ was selected within this range.

Further, as shown in FIG. 3, the tapered insulating portion 16C of the insulated high voltage lead wire 16 is located inside the insulating barrier 18, so that much insulation is not required. On the other hand, if the insulation at the grooved portion is too strong, a large potential will be shared even within the insulating purrier 18. Since this reduces the insulation effect of the insulation barrier 18, it can be said that thick insulation is a bad insulation shape. Therefore, the shape is good in workability and does not affect the insulation ability of the insulation barrier 18, that is, it is formed to have tapered insulation from the mounting portion 22 to the lower terminal 14.

〔Effect of the invention〕

As explained above, according to the present invention, an insulation barrier consisting of a cylindrical part and an inclined part surrounding a part of the lower part of the bushing and the outer peripheral part of the insulation shield attached to the lower terminal of this bushing is installed. The insulated high-voltage lead wire is attached to the insulated high-voltage lead wire through the insulating barrier, and the insulating layer of the insulated high-voltage lead wire inside this insulating barrier is made of tapered insulation, thereby reducing the electric field E at the lower end of the bushing and the electric field E of the insulated high-voltage lead wire. It is possible to provide a direct current electric appliance that can significantly reduce the amount of heat and thereby strengthen the insulation of the connection between the bushing and the insulated high voltage lead wire.

[Brief explanation of drawings]

Fig. 1 is a partially sectional front view and electric field distribution diagram showing the bushing connection part of a conventional self-current oil-immersed transformer, Fig. 2 is a partially sectional side view of the DC oil-immersed transformer of the present invention, and Fig. 3 is a cross-sectional view of the oil submerged side of the bushing in Fig. 2, Fig. 4 is a diagram showing the relationship between the electric field E1 and the length of the cylindrical part, and Fig. 5 is a diagram showing the relationship between the electric field E2 and the angle θ of the inclined part. It is a line diagram showing a relationship. 11...Transformer tank, 11a...Iron core, 11b.
・・Coil, 11C・Insulating oil, 12・Bushing pot part, 13・Bushing, 14・・Lower terminal, 1
5. Insulating shield, 15a... Insulating layer, 16... Insulated high voltage lead wire, 16a... Lead wire, 16b... Insulating layer, 16C... Tapered insulation part, 17... Connection part, 1
8... Insulation barrier, 18a19. #l oblique part, 18b
...Cylindrical part, 20...Oil-filled side paddle pipe, 21...Center conductor, 21a...Insulating core, 22...Mounting part, imperial line...
・Horizontal axis. Agent Patent Attorney Inoue - Male Figure 1 Figure 2 Figure 3 Figure 4 OLt ZL7 JLt 4Lt

Claims (4)

[Claims] (1) In a DC oil-filled electrical equipment that has a connecting part between the lower terminal of the bushing attached to the bushing pocket and the insulated high-voltage lead wire that is connected to the coil of the electrical equipment body, the outer periphery of the insulated high-voltage lead wire It surrounds the outer periphery of the insulation shield provided at the bottom of the bushing, and
A direct current oil-filled electrical device characterized in that an insulating barrier is provided on one side of the insulated high-voltage lead wire through a mounting portion and in contact with the outer periphery of the insulating shield. (2) The insulation barrier is formed of a press board, and the length L2 is between the axial length L2 of the cylindrical part of the insulation barrier located on the outer periphery of the insulation shield and the axial length Ll of the insulation shield. The blood flow oil-filled electrical device according to claim 1, which is selected to have a relationship of 2L+. (3) The angle θ that the inclined part of the insulation barrier makes with the horizontal axis is 4
A DC oil-filled electric appliance according to claim 1, wherein the angle is 5° to 60°. (4) The DC oil-filled electrical equipment according to claim 1, wherein the insulated high-voltage lead wire is tapered insulated from the mounting portion on the insulated high-voltage lead wire at the portion cored by the insulating barrier to the lower terminal of the bushing.